Window Functions vs GROUP BYs

There are many options available for improving the performance of a query: indexes, statistics, configuration settings, etc… However, not all environments allow you to use those features (eg. vendor...
The...

Database Fundamentals #21: Using the JOIN Operator, OUTER JOIN

The OUTER JOIN returns one complete set of data and then the matching values from the other set. The syntax is basically the same as INNER JOIN but you...

Extract the Path from Filename in SQL

While I was preparing an article, I faced the challenge to extract the path from a filename in SQL Server. It’s an interesting challenge with many possible uses, so I...

Why Rolling back inserts with Identity columns is a bad idea.

It wasn’t until the other day that I realised what the behaviour was when rolling back a transaction with an insert on a table with an identity column, to...

The Difference Between SQL’s JOIN .. ON Clause and the Where Clause

A question that is frequently occurring among my SQL training‘s participants is: What’s the difference between putting a predicate in the JOIN .. ON clause and the WHERE clause?...

Writing Crossword puzzles with a database: T-SQL Tuesday #113

Todd Kleinhans (b/t) is host for T-SQL Tuesday this month and wants us to talk about how we use databases ... Continue reading
The post Writing Crossword puzzles with a...

Data Type Precedence and Implicit Conversions

SQL Server needs to make sure data types match when performing operations that involve multiple pieces of data. When the data types do not match, SQL Server has to...
The...

Using JSON for matrices in SQL Server.

From SQL Server 2017, it becomes more practical to use JSON arrays for representing and processing a matrix. SQL Server can read them, and update values in them but...

Finding a character in every character string by elimination

Using a number’s table, you can break down every value in a column into one character per row, and then do some analysis. In our case, I want to find a bad character, by eliminating known acceptable characters.

Getting the columns